【BeagleBone Black试用体验】+ 第十四篇 ☞给BBB写个1602驱动

ti

有了led驱动的经验，自己也尝试着写了个1602的驱动，引脚定义：

源码如下：

#include
#include
#include
#include // Required for the GPIO functions
#include
#include
#include
static struct class *lcd_class;
static struct device *lcd_drv;
MODULE_LICENSE("GPL");
MODULE_AUTHOR("yang yongsheng");
MODULE_DESCRIPTION("A LCD test driver for the BBB");
MODULE_VERSION("0.1");
static unsigned int D7 = 69; ///< hard coding the LCD_D7 gpio for this example to P8_9
static unsigned int D6 = 68; ///< hard coding the LCD_D7 gpio for this example to P8_10
static unsigned int D5 = 67; ///< hard coding the LCD_D7 gpio for this example to P8_8
static unsigned int D4 = 66; ///< hard coding the LCD_D7 gpio for this example to P8_7
static unsigned int EN = 45; ///< hard coding the LCD_D7 gpio for this example to P8_11
static unsigned int RW = 44; ///< hard coding the LCD_D7 gpio for this example to P8_12
static unsigned int RSET = 23; ///< hard coding the LCD_D7 gpio for this example to P8_13
//static bool On = 0; ///< Is the LED on or off? Used to invert its state (off by default)
static unsigned int major;
#define LCD1602_MAGIC 'L'
#define LCD_CLR _IO(LCD1602_MAGIC, 0)
#define LCD_ONE _IO(LCD1602_MAGIC, 1)
#define LCD_TWO _IO(LCD1602_MAGIC, 2)
void wr4port(char value)
{
unsigned char temp,i;
i=0;
switch(i)
{
case 0:temp=value&0x01;if(temp == 1) gpio_set_value(D4,true);else gpio_set_value(D4,false);i++;
case 1:temp=value&0x02;if(temp == 0x02) gpio_set_value(D5,true);else gpio_set_value(D5,false);i++;
case 2:temp=value&0x04;if(temp == 0x04) gpio_set_value(D6,true);else gpio_set_value(D6,false);i++;
case 3:temp=value&0x08;if(temp == 0x08) gpio_set_value(D7,true);else gpio_set_value(D7,false);i++;break;
default: break;
}
}
void wrcom(char com)
{
gpio_set_value(EN,false);
gpio_set_value(RW,false);
gpio_set_value(RSET,false);
wr4port(com>>4);
udelay(10);
gpio_set_value(EN,true);
udelay(10);
gpio_set_value(EN,false);
wr4port(com);
udelay(10);
gpio_set_value(EN,true);
udelay(10);
gpio_set_value(EN,false);
}
void wrdat(char dat)
{
gpio_set_value(EN,false);
gpio_set_value(RW,false);
gpio_set_value(RSET,true);
wr4port(dat>>4);
udelay(10);
gpio_set_value(EN,true);
udelay(10);
gpio_set_value(EN,false);
wr4port(dat);
udelay(10);
gpio_set_value(EN,true);
udelay(10);
gpio_set_value(EN,false);
}
static int lcd_open(struct inode *inode, struct file *file)
{
printk("bbb's led gpio60 will open.n");
wrcom(0x28);
msleep(5);
wrcom(0x0f);
msleep(5);
wrcom(0x06);
msleep(5);
wrcom(0x80);
msleep(5);
return 0;
}
static ssize_t lcd_write (struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
char val[17];
char i = 0;
printk("write bbb's lcd.n");
copy_from_user(val, buf, count);
while((val[i] != '\0')&&(i
{
wrdat(val[i]);
i++;
}
return 0;
}
static ssize_t lcd_read (struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
return 0;
}
static long lcd_ioctl (struct file *file, unsigned int cmd, unsigned long arg)
{
switch(cmd)
{
case LCD_CLR:
wrcom(0x01);break;
case LCD_ONE:
wrcom(0x80);break;
case LCD_TWO:
wrcom(0xc0);break;
default:
printk("unknown command.n");
}
return 0;
}
static struct file_operations lcd_fops = {
.owner = THIS_MODULE,
.open = lcd_open,
.write = lcd_write,
.read = lcd_read,
.unlocked_ioctl = lcd_ioctl,
};
static int __init lcd_init(void){
int result = 0;
printk(KERN_INFO "GPIO_TEST: Initializing the LCD_GPIO LKMn");
// Is the GPIO a valid GPIO number (e.g., the BBB has 4x32 but not all available)
if (!gpio_is_valid(D7)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_D7n");
return -ENODEV;
}
if (!gpio_is_valid(D6)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_D6n");
return -ENODEV;
}
if (!gpio_is_valid(D5)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_D5n");
return -ENODEV;
}
if (!gpio_is_valid(D4)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_D4n");
return -ENODEV;
}
if (!gpio_is_valid(RW)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_RWn");
return -ENODEV;
}
if (!gpio_is_valid(EN)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_ENn");
return -ENODEV;
}
if (!gpio_is_valid(RSET)){
printk(KERN_INFO "GPIO_TEST: invalid LCD_RSETn");
return -ENODEV;
}
// Going to set up the LED. It is a GPIO in output mode and will be on by default
gpio_request(D7, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(D7, false); // Set the gpio to be in output mode and off
gpio_export(D7, false); // Causes gpio49 to appear in /sys/class/gpio
gpio_request(D6, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(D6, false); // Set the gpio to be in output mode and off
gpio_export(D6, false);
gpio_request(D5, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(D5, false); // Set the gpio to be in output mode and off
gpio_export(D5, false);
gpio_request(D4, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(D4, false); // Set the gpio to be in output mode and off
gpio_export(D4, false);
gpio_request(RW, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(RW, false); // Set the gpio to be in output mode and off
gpio_export(RW, false);
gpio_request(EN, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(EN, false); // Set the gpio to be in output mode and off
gpio_export(EN, false);
gpio_request(RSET, "sysfs"); // gpioLED is hardcoded to 60, request it
gpio_direction_output(RSET, false); // Set the gpio to be in output mode and off
gpio_export(RSET, false);
major = register_chrdev(0,"bbb_lcd",&lcd_fops); //注册字符驱动
lcd_class = class_create(THIS_MODULE,"bbb_lcd");
lcd_drv = device_create(lcd_class,NULL,MKDEV(major,0),NULL,"lcd1602");
return result;
}
static void __exit lcd_exit(void){
gpio_set_value(D7, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(D7); // Unexport the LCD GPIO
gpio_free(D7); // Free the LCD GPIO
gpio_set_value(D6, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(D6); // Unexport the LCD GPIO
gpio_free(D6); // Free the LCD GPIO
gpio_set_value(D5, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(D5); // Unexport the LCD GPIO
gpio_free(D5); // Free the LCD GPIO
gpio_set_value(D4, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(D4); // Unexport the LCD GPIO
gpio_free(D4); // Free the LCD GPIO
gpio_set_value(RW, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(RW); // Unexport the LCD GPIO
gpio_free(RW); // Free the LCD GPIO
gpio_set_value(RSET, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(RSET); // Unexport the LCD GPIO
gpio_free(RSET); // Free the LCD GPIO
gpio_set_value(EN, false); // Turn the LCD off, makes it clear the device was unloaded
gpio_unexport(EN); // Unexport the LCD GPIO
gpio_free(EN); // Free the LCD GPIO
unregister_chrdev(major,"bbb_lcd"); //卸载字符驱动
printk(KERN_INFO "LCD_TEST: Goodbye from the LKM!n");
}
module_init(lcd_init);
module_exit(lcd_exit);